A strain of staph emerged in hospitals in the past that was resistant to the broad-spectrum antibiotics commonly used to treat it. Termed methicillin-resistant Staphylococcus aureus (MRSA), it was one of the first germs to resist all but the most powerful drugs. MRSA infection can be fatal.
Staph bacteria are normally found on the skin or in the nose of about one-third of the population. If you have staph on your skin or in your nose, but aren't sick, you are said to be "colonized" but not infected with MRSA. Healthy people can be colonized with MRSA and have no ill effects, however they can pass the germ on to others.
Staph bacteria are generally harmless unless they enter the body through a cut or other wound, and even then they simply cause only minor skin problems in healthy people. In older adults and people who are ill or have weakened immune systems, ordinary staph infections can cause a serious illness.
In the 1990s, a type of MRSA began showing up in the wider community. Today that form of staph, known as "community-associated MRSA", or "CA-MRSA", is responsible for many serious skin and soft tissue infections and for a serious form of pneumonia.
Causes of MRSA
Although the survival tactics of bacteria contribute to antibiotic resistance, humans bear most of the responsibility for the problem. Leading causes of antibiotic resistance include:
- Unnecessary antibiotic use in humans.
- Antibiotics in food and water.
- Germ mutation.
Like other superbugs, MRSA is the result of decades of excessive and unnecessary antibiotic use. For years, antibiotics have been prescribed for colds, flu and other viral infections that don't respond to these drugs, as well as for simple bacterial infections that normally clear up on their own.
Prescription drugs aren't the only source of antibiotics. In the United States, antibiotics can be found in beef cattle, pigs and chickens. The same antibiotics then find their way into municipal water systems when the runoff from feedlots contaminates streams and groundwater.
Routine feeding of antibiotics to animals is banned in the European Union and many other industrialized countries. Antibiotics given in the proper doses to animals that are sick don't appear to produce resistant bacteria.
Even when antibiotics are used appropriately, they contribute to the rise of drug-resistant bacteria because they don't destroy every germ they target.
Bacteria live on an evolutionary process, so germs that survive treatment with one antibiotic soon learn to resist others, and because bacteria mutate much more quickly than new drugs can be produced, some germs end up resistant to just about everything. That's why only a handful of drugs are now effective against most forms of staph.